XML 52 R41.htm IDEA: XBRL DOCUMENT v3.7.0.1
Components of Net Periodic Benefit Costs (Detail) - Deferred Compensation Plan - USD ($)
$ in Thousands
3 Months Ended 9 Months Ended
Jan. 31, 2017
Jan. 31, 2016
Jan. 31, 2017
Jan. 31, 2016
Defined Benefit Plan Disclosure [Line Items]        
Service cost $ 1,793   $ 3,981  
Interest cost 1,062 $ 703 3,185 $ 2,109
Amortization of actuarial loss 763 730 2,289 2,192
Expected return on plan assets (389)   (1,169)  
Net periodic benefit costs $ 3,229 $ 1,433 $ 8,286 $ 4,301